1. Field of the Invention
The present invention relates generally to key switch assemblies and more particularly, to a watertight key switch assembly, which is bendable and washable with water, and superior in weather-resisting property. The invention relates also to the fabrication of such a watertight key switch assembly.
2. Description of the Related Art
A mobile digital data playing apparatus, for example, mobile CD/VCD/DVD player or MP3 player has been intensively used by many people as one's mobile personal music-playing device. These digital data playing apparatus are high-precision electronic products. When a digital data playing apparatus is exposed to a high or low temperature environment for a long period of time, the internal electronic component parts may become abnormal, failing to function well. Further, these electronic products are commonly equipped with key switches for operation. However, regular key switches are inferior in waterproof property. When wetted, the electronic components on the inside circuit board may be damaged, resulting in malfunctioning of the product.
There are manufacturers who provide waterproof key switches. Taiwan Patent Publication No. M269556, issued on Jul. 1st, 2005, entitled “Waterproof key switch”, shows an example. According to this design, the waterproof key switch comprises a hard key cap, a flexible key switch holder, a hard bottom plate having a plurality of switches, and a hard shell covering the hard bottom plate. The key cap has a plunger downwardly extended from the bottom side thereof and inserted through a through hole on the key switch holder. This design of key switch has a waterproof characteristic. However, when the key switch is dipped in water, water will go through the through hole on the key switch holder to wet the switches, loosing its waterproof capability.
Further, U.S. Pat. No. 5,087,606 discloses a waterproof key switch design entitled “Waterproof switch with single contact and method for manufacturing same”. According to this design, the waterproof switch has a single contact arranged in a sealed housing, with an actuator arm protruding from one end and electrical terminals protruding from an opposite end. The single contact is arranged close to a metal portion that is moved by the actuator into mechanical and electrical contact with the single contact. The sealed housing is formed of two pieces that are attached by a heat activated adhesive. The switch can be assembled by forming the metal switch parts on a long strip and subsequently, following the assembly of the housing, the small metal portions joining the switch parts are sheared away. This design of switch assembly is function and waterproof. However, the hard material property of the housing does not allow bending of the switch assembly, limiting the applicability of the switch assembly. Further, when the switch assembly is mechanically washed with water, the internal parts may be forced out of place, loosing the waterproof capability of the switch assembly.
Therefore, it is desirable to provide a watertight key switch assembly that eliminates the aforesaid drawbacks.